(AFP) - Belgian police shot a suspect as part of a huge Europeanterror crackdown that netted several arrests Friday as France's president said a jihadist network that targeted both Paris and Brussels was being "destroyed".

Grieving Belgians held prayers in the rain in a central Brussels square carpeted with flowers and tributes to the 31 dead and 300 wounded in Tuesday's carnage, but there was also growing anger at the government for letting a string of militants slip through the net.

The raids came as under-fire Belgian investigators uncovered alarming new evidence of a European jihadist cell tied to bombings at Brussels' airport and metro, November's Paris attacks and a new French plot.

"Even if the one that committed the attacks in Paris and Brussels is in the process of being destroyed... there is still a heavy threat," French President Francois Hollande said.

The Belgian government has admitted "errors" and two ministers offered to resign after Turkey said Ibrahim El Bakraoui, who blew himself up in the airport attack, had been arrested and deported and that Belgium had ignored warnings that he was a "foreign terrorist fighter".

Ibrahim and his brother Khalid, the suicide bomber in the metro attack, were also on a US counterterrorism watch list, CNN reported.

Ibrahim was on the list even before the November Paris attacks while Khalid was added soon after. Prosecutors have confirmed Khalid was the subject of an international warrant over the Paris attacks.

European authorities are under huge pressure to better coordinate the tracking of homegrown extremists and fighters returning from Syria, as evidence grows of a thriving jihadist network straddling France and Belgium.

- Suspect shot in leg -

French police said they had foiled a terror strike in France by 34-year-old Reda Kriket -- a man previously convicted in Belgium in a terror case alongside Paris attacks ringleader Abdelhamid Abaaoud -- after arresting him and discovering explosives at his home.

Belgian police later arrested three people in connection with the new French conspiracy, prosecutors said.

In dramatic scenes, one of the suspects was shot in the leg at a tram stop in broad daylight in a huge operation by police in the Belgian capital's Schaerbeek district, where police this week found a bomb factory linked to the Brussels attacks.

Deepening the links, Belgian prosecutors revealed that Brussels airport bomber Najim Laachraoui's DNA was found on a suicide vest and a piece of cloth at the Bataclan concert hall where 90 people were killed during November's Paris attacks, and on a bomb at the Stade de France stadium.

A huge manhunt is still under way for at least two suspects -- one of the airport attackers whose bomb failed to go off and another man seen in the metro with the bomber there.

Investigators also say Khalid El Bakraoui rented an apartment in Brussels used by key Paris suspect Salah Abdeslam, who was taken into custody in the Belgian capital on March 18.

The nation's federal prosecutor revealed Abdeslam "has invoked his right to silence" and has not spoken to investigators since a few brief interviews the day after his arrest.

- 'Covered in blood' -

US officials confirmed that two Americans were among the Brussels dead. Secretary of State John Kerry said he stood by the Belgian people, echoing their backing for the United States after the 9/11 attacks.

"Then, voices across Europe declared, 'Je suis Americain'. Now, we declare, 'Je suis Bruxellois' and 'Ik ben Brussel,' Kerry said in French and Flemish, the country's two main languages, after meeting Belgian Premier Charles Michel.

Harrowing stories continued to emerge from survivors of the attacks, in which people of around 40 nationalities were killed or wounded.

Briton David Dixon, 51, who lived in Brussels, texted his aunt after the airport blasts to say he was safe, but happened to be on the metro system when a suicide bomber blew himself up, British media said.

A 19-year-old Mormon missionary was at the Delta airlines check-in counter when the explosions went off at Zaventem.

"My body was actually picked up off the ground for a moment," Mason Wells told CNN. "My left shoe was blown off and a large part of the right side of my body got really hot and then really cold and I was covered in... a lot of blood that wasn't mine."

Officials confirmed the deaths of young Dutch siblings Sascha and Alexander Pinczowski, who were reportedly on the phone with relatives when the airport bomb went off.

Among only three fatalities formally named so far are Peruvian Adelma Marina Tapia Ruiz, 37. Her husband Christophe Delcambe, and their three-year-old twin daughters, only survived because the girls had run off and their father had chased after them.

A Chinese national was also confirmed among those killed.

Belgium has lowered its terror alert to the second-highest level for the first time since the attacks, but the police and military presence on the streets of the capital remains high.